It is a surgical operation to repair cranial defects caused by various reasons, which requires incision of the scalp, exposure of the bone window, and placement of a special cranial substitute adapted to the physiological environment of the human head to reconstruct a complete and closed cranial cavity. A complete and closed cranial cavity environment is very important, if the long-term cranial defect state will cause a lot of damage to the body, causing a series of cranial defect syndrome, and may even be life-threatening. Therefore, when cranial defect occurs, cranial repair should be actively carried out in time to solve the problems such as no effective protection of brain tissue in the defective area, blood supply disorder, abnormal cerebrospinal fluid circulation, etc., as well as to reshape the beautiful skull shape. However, after all, it is a foreign body that needs to be implanted in the body, and many patients are concerned about the problem of rejection. Indeed, this requires the selection of quality cranial repair materials. Titanium mesh, which is widely used in many hospitals, is not ideal and can lead to rejection reactions, resulting in the destruction of scalp tissue and serious consequences. In addition, postoperative infection, poor healing of incision, material exposure, postoperative cold and heat sensitivity, poor shaping effect, etc. may occur. Therefore, titanium mesh is not a very ideal material for cranial repair. The most ideal cranial repair material is polyetheretherketone PEEK, which is becoming the latest trend in cranial repair materials because of its excellent performance. So will peek repair cranial bone rejection? The properties of PEEK are basically very close to those of autologous cranial bone, and its histocompatibility is very good, and no rejection will occur. There are no clinical reports of rejection after peek repair of cranial bone.